Dr. Vonnegut became fascinated with science
when he was young, and his curiosity about the world around him
continued for the rest of his life. Although he was initially
educated as a chemist, his interests ranged far beyond, into
meteorology, cloud physics, atmospheric electricity, aerosols and many
other fields. He made significant contributions in many, widely
separated fields. For example, as the result of his curiosity
about the behavior of liquids, in the early 1950s, he devised a unique
method for measuring the low surface tensions of surfactants now used
in the secondary recovery of petroleum from nearly depleted oil wells.

Bernard Vonnegut is best known, however, for
his discovery on November 14, 1946 at the General Electric Research
Laboratory of the effectiveness of silver iodide as ice-forming nuclei
that has been widely used to seed clouds in efforts to augment
rainfall. While observing copious rainfalls from clouds
everywhere warmer than 0o C during a 1949 expedition to Puerto Rico,
Dr. Vonnegut recognized that snow was not essential for the formation
of rain, and he began to study the formation of precipitation due to
cloud droplet collision and coagulation. He studied how colliding
droplets, formed above a vertical fountain, often rebound without
coalescing because of an intervening, thin boundary of air that is not
expelled during the brief encounter. He then discovered, as had
Rayleigh in 1879, that the presence of feeble electric forces enhanced
coalescence and formation of larger drops, during such
collisions. Colliding droplets coalesced instead of rebounding
when electrical space charges he created in the air across the room
drifted past his fountain. This discovery led him to speculate that
also in clouds electrical charges could aid in the coalescence of
droplets and thus initiate rainfall. This idea was counter to the
prevailing view, that cloud electrification is caused by the fall of
charged precipitation, and electrically-induced coalescence between
cloud droplets could only be of secondary interest since the electric
effects could not take place until appreciable rain was already formed
and falling.

Since there was little evidence to support
the precipitation idea, Vonnegut began his own speculations as to how
clouds become electrified. He proposed an inductive mechanism for
the electrification of convective clouds in which ions in the air
around the clouds become attached to cloud particles and thereafter are
carried by the motions of the cloud. He argued that the Wilson
current of negative ions that flows to the positively-charged tops of
thunderclouds and the point-discharge positive ions that are carried
from the Earth toward an electrified cloud base were not necessarily
dissipative of cloud electrification. Some of these ions could be
moved in the convective overturn associated with a growing cloud,
resulting in point discharge ions being carried by updrafts high in the
cloud where they attract more negative ions to the cloud. These in turn
become attached to cloud particles near the cloud boundary and are
transported downward by the unfolding and downward motions of air in
and around a growing cloud. The thundercloud thus acts as an
electrostatic influence machine with positive feedback driven by
convection in which the Wilson and point discharge currents increase
the electrification.

He proposed this idea as a possible
alternative or supplement to the widely-held view that lightning is
caused by sedimentation of charged precipitation elements in a neutral
cloud. While he was never convinced that his ideas about the role of
convection were adequate to explain cloud electrification, he was
pleased that they suggested experiments that might add to an
understanding of cloud processes. He carried out many ingenious
experiments, including the widespread releases of ions into the air to
test the effect of priming clouds with negative space charges. As
he predicted, interesting, anomalous polarity clouds developed over his
sources of negative charge that suggested the operation of an influence
electrification mechanism. The final assessment of his ideas
about the role of convection in cloud electrification has, however, not
been made because we still have little information about the fate of
the Wilson current and on the trajectories of air parcels in the upper
regions of a convective cloud.

After observing the giant clouds and the
incredibly frequent lightning associated with the storm that produced a
devastating tornado in Worcester, MA on June 9, 1953, Vonnegut
suggested that there might be a connection between the vigorous
electrification and the intense winds associated with the
tornado. He proposed that the kinetic energy concentration in a
tornado funnel perhaps was a result of repeated lightning discharges in
the same column of air, heating it and causing a strong local updraft
as had been observed in the fire whirlwinds that develop over large
conflagrations. He also wondered whether the electric wind that
arises when high space charge concentration is acted upon by strong
electric fields could play a role in concentrating the angular
momentum. His observation, that the clouds associated with the
Worcester storm penetrated high into the stratosphere, led him analyze
the vertical velocities required for such penetration. His result
of a 100 m/s updrafts surprised the meteorologists at the time, many of
whom had assumed cloud growth was limited at the tropopause. The
low temperatures he calculated at the storm cloud top is today measured
from satellites and is widely used as an index of storm severity.
Vonnegut recognized also that the negative buoyancy and eventual
collapse of these cold overshooting turrets was the cause of upper
level downdrafts in thunderclouds, that could carry the electric charge
deposited on the turret by the Wilson current deep into the cloud.

His summer expeditions to the mountains of
New Mexico for the study of thunderclouds with his colleagues and
friends at New Mexico Tech in Socorro, were times of productive delight
and inspiration. Noting that the intense rain that fell often did
not exist in the cloud prior to the electric discharge, they proposed
an electrostatic precipitation explanation based on the re-arrangement
of charges around the lightning channels. Noting that long,
grounded wires carried aloft by balloons into thunderclouds escaped
being struck by lightning, they realized that the wires protected
themselves by their great emissions of point discharge ions.
However, after further experimentation using the van de Graaf generator
at the Museum of Science in Boston, they found that sparks could be
initiated from a wire by making its tip move rapidly in a strong
electric field. This discovery led to the modern successes in
initiating lightning by rapidly injecting wires, using rockets, into
thunderstorms.

With associates, Vonnegut invented, designed
and built instruments for his studies. These include a continuous
condensation nuclei counter, a devise for measuring the true speed of
moving, compressible fluids, an electrostatic generator of uniform
aerosol particles, and instruments for measuring the electric fields
and space charges in the free air. He devised a simple detector
for providing warnings of strong electric fields by sensing the point
discharge currents that flow into the air from exposed, sharp
conductors under the strong electric fields. He devised a housing
for thermometers used for making air temperature measurements in
weather reconnaissance that eliminated the error caused by adiabatic
compression of the air ahead of the thermometer. He investigated
the behavior of evaporating, charged drops, suspended in an electric
field. In 1963, when a volcano erupted under the North Atlantic,
forming the island Surtsey, Vonnegut made measurements from a fishing
vessel of the electrification produced by the plume ejected from the
crater. His findings caused other investigators to follow; the
joint results provide the most extensive study of volcanic
electrification processes now available.

In 1967, after 15 years of productive
scientific activities at Arthur D. Little, Inc. in Cambridge MA, Dr.
Vonnegut joined the Atmospheric Sciences Research Center as a research
scientist and the Department of Atmospheric Science as a professor at
the State University of New York at Albany. At the University, he
taught courses in atmospheric chemistry, electricity and
instrumentation while continuing his studies into atmospheric
processes. With students and colleagues in Albany he
studied a variety of phenomena. They devised a solid-solution aerosol
of silver iodide and silver bromide that eliminated the -4o C threshold
for the initiation of ice nucleation when silver iodide nuclei were
used. They devised an instrument that determined how strong the
electric fields over water surfaces could be without corona
emissions. They developed a method of monitoring global
electrification by measuring the potential of the Earth relative to the
upper atmosphere. They determined the minimum electric field
strength at which positive streamers propagate. They studied the
stochastic nature of ice nucleation and pointed out that time of
exposure of the nucleus was important in rating its efficacy as an
ice-nucleating agent. They investigated behavior of miniature
"tornadoes" generated in the laboratory by electrical forces.
They devised instruments for laboratory simulation of raindrop size
distributions. They built and analyzed an instrument for real
time measurements of rain rate. They invented and analyzed a
unique oscillatory anemometer, and a miniature cell for real time
measurements of the electrical conductivity of rain. At the same
time his main concern was the electrification of thunderclouds.

Vonnegut was long interested in lightning
discharges and their effects on clouds. He began measuring the
intensity of light scattered and emitted from thunderclouds and soon
discovered a relatively long-lasting transient increase in the light
level after lightning discharge within a cloud. He was able to
demonstrate that the transient was caused by the reflection of sunlight
from ice crystals oriented by the changing electric fields after a
discharge. This effect is now being used with a
multi-polarization radar to locate regions of strong and changing
electric fields in thunderclouds. The reports of spectacular
lightning seen from the Skylab in Earth orbit inspired him to study
lightning from above. He and associates photographed lightning
from high altitude balloons. He and other associates made
electrical measurements and photographs from U-2 airplanes flying over
thunderclouds and, with associates at NASA he obtained video recordings
of lightning from space. They confirmed eye-witness accounts they
had compiled of electrical discharges propagating upward from the tops
of thunderclouds. This study has now expanded into research
projects dedicated to understanding upward-going SPRITES, Blue Jets and
Elves.

In 1984, Dr. Vonnegut was honored by the
State University at Albany with the appointment as Distinguished
Research Professor. When he formally retired the following year,
he became Professor Emeritus and continued teaching and pursuing his
research interests for the rest of his life. He published more
than 190 refereed papers and reports, many of them by himself and
others with students and colleagues with whom he worked and stimulated
by his ideas. More than thirty of his papers were published after
his nominal retirement in 1985. Two more papers were in press at
the time of his death in late April, 1997. He supplied articles
to 4 encyclopedias, was co-author of five books and was the recipient
of 28 patents. Through the years he served on many advisory
boards and panels. His quiet, unassuming manner and his tenacity
in pursuing an understanding of the natural phenomena in the world
around him led one of his friends to dub him, "The Gentle
Iconoclast". He was an inspiration to his colleagues and to his
students who remember him fondly. His last paper, which he edited
from his bed by incorporating a reviewer's suggestions, was aimed at
setting straight the old, discredited but tenaciously held view by some
meteorologists that updrafts are the only significant air motions in
growing cumuli. His first submission of his convective
electrification mechanism had been rejected in 1955 in part on that
basis and, despite some improvement in the understanding of convection
in the later years, he took final issue with a recent revival of that
simplistic view of motions in active clouds.

Bernard Vonnegut's legacy includes his lucid
expositions of nature's behavior, his engaging approach to teaching and
his inspiring students and colleagues with curiosity and imagination.